The demographics of sexual orientation vary significantly, and estimates for the LGBT population are subject to controversy and ensuing debates.

Obtaining precise number is difficult for a variety of reasons. One of the major reasons for the difference in statistical findings regarding homosexuality and bisexuality has to do with the nature of the research questions. Major research studies on sexual orientation are discussed. Most of the studies listed below rely on self-report data, which poses challenges to researchers inquiring into sensitive subject matter. More importantly, the studies tend to pose two sets of questions. One set examines self-report data of same-sex sexual experiences and attractions while the other set examines self-report data of personal identification as homosexual or bisexual. Fewer research subjects identify as homosexual or bisexual than report having had sexual experiences or attraction to a person of the same sex. Several studies of sexual orientation in countries provide comparative perspectives. Tables comparing several U.S. cities' population numbers are also included. However, since many individuals may fail to report outside the heterosexual norm or define their sexuality in their own unique terms, it is difficult to fully grasp the size of the LGBT population. The type of survey being used and the type of setting a subject is in while being surveyed may also affect the answer that the subject gives.

Another significant distinction can be made between what medical statisticians call incidence and prevalence. For example, even if two studies agree on a common criterion for defining a sexual orientation, one study might regard this as applying to any person who has ever met this criterion, whereas another might only regard him/her as being so if they had done so during the year of the survey. According to the American Psychological Association, sexual orientation refers to an "enduring pattern of emotional, romantic, and/or sexual attractions to men, women, or both sexes", as well as to "a person's sense of identity based on those attractions, related behaviors, and membership in a community of others who share those attractions."[1] Therefore, a person can be celibate and still identify as being bisexual or homosexual based on romantic proclivities.[2]

Western perception of homosexuality versus the rest of the world[edit]

The population that has come to be referred to as "gay" in the West is not a descriptive term that would be recognized by all men who have sex with men (MSM) as known in the rest of the world. While gay culture is increasingly open and discussed, the world of MSM consists of a diverse population that often may respond differently depending on how communications in clinical settings are framed. "Gay" is generally used to describe a sexual orientation, while "MSM" describes a behavior.[3]

Some men who have sex with other men will not relate to the term "gay" or homosexual, and do not regard sex with other men as sexual activity, a term they reserve for sexual relations with women. This is particularly true among individuals from non-Western cultures. Nevertheless, it is common in the US. Terms such as MSM or "same gender loving" are often used in place of the word gay. Men in Africa and Latin America engage in sexual relationships with other men while still referring to themselves as "heterosexual", which is known as being on the "down-low".[4] The same is true of men who engage in homosexual activities in the military, gender-segregated schools and universities, or prison; most of them do not consider themselves gay but still engage sexually with members of their own sex in order to fulfill their desires, exercise power, gain favors, or for other reasons.[5]

There is a lack of information on sexual behaviour in most developing countries. The limited sources that are available indicate that although homosexual self-identification might occur relatively infrequently, the prevalence of homosexual behaviour is higher. These men are not taken into consideration in some sexual identity surveys which may lead to under-reporting and inaccuracies.[6]

Reliable data on the size of the gay and lesbian population would be valuable for informing public policy.[7] For example, demographics would help calculate the costs and benefits of domestic partnership benefits, of the impact of legalizing gay adoption.[7] Further, knowledge of the size of the "gay and lesbian population holds promise for helping social scientists understand a wide array of important questions—questions about the general nature of labor market choices, accumulation of human capital, specialization within households, discrimination, and decisions about geographic location."[7]

Two of the most famous studies of the demographics of human sexual orientation were Dr. Alfred Kinsey's Sexual Behavior in the Human Male (1948) and Sexual Behavior in the Human Female (1953). These studies used a seven-point spectrum to define sexual behavior, from 0 for completely heterosexual to 6 for completely homosexual. Kinsey concluded that a small percentage of the population were to one degree or another bisexual (falling on the scale from 1 to 5). He also reported that 37% of men in the U.S. had achieved orgasm through contact with another male after adolescence and 13% of women had achieved orgasm through contact with another woman.[8]

Paul Gebhard, Kinsey's former colleague and successor as director of the Kinsey Institute for Sex Research,[10] dedicated years to reviewing the Kinsey data and culling what he claimed were its purported contaminants. In 1979, Gebhard (with Alan B. Johnson) concluded that none of Kinsey's original estimates were significantly affected by the perceived bias, finding that 36.4% of men had engaged in both heterosexual and homosexual activities, as opposed to Kinsey's 37%.

Recent critiques of these studies have suggested that, because of their dependence on self-identification, they may have undercounted the true prevalence of people with a history of same-sex behavior or desire.

The then largest and most thorough survey in Australia was conducted by telephone interview with 19,307 respondents between the ages of 16 and 59 in 2001/2002. The study found that 97.4% of men identified as heterosexual, 1.6% as homosexual and 0.9% as bisexual. For women 97.7% identified as heterosexual, 0.8% as lesbian and 1.4% as bisexual. Nevertheless, 8.6% of men and 15.1% of women reported either feelings of attraction to the same gender or some sexual experience with the same gender.[11] Overall, 8.6% of women and 5.9% of men reported some homosexual experience in their lives; these figures fell to 5.7% and 5.0% respectively when non-genital sexual experience was excluded.[12] Half the men and two thirds of the women who had same-sex sexual experience regarded themselves as heterosexual rather than homosexual.[13]

2012-2013

An update on the above study; it employs the same methodology, has a larger sample (20,055 respondents),[14] and a broader respondent age range (16–69). The study found that 96.5% of the entire sample (or 96.8% of the men and 96.3% of the women) identified as heterosexual, a drop from the 2003 findings (97.5%).[15] Homosexuals accounted for 1.9% of the male population and 1.2% of the female population, a non-significant difference between the sexes. Bisexuals accounted for 1.3% of the male population and 2.2% of the female population. Women were significantly more likely than men to identify as bisexual, and less likely to report exclusively other-sex or same-sex attraction and experience. Similarly, more women reported same-sex experience and same-sex attraction. Nine percent of men and 19% of women had some history of same-sex attraction or experience. More women identified as lesbian or bisexual than in 2001–02. Homosexual/gay identity was more common among men with university education and living in cities, and much less common among men with blue-collar jobs. Both male and female bisexuality were more common among respondents under the age of 20. Male bisexuality was also overrepresented among men in their sixties.[14]

2006–2014

In interviews with 180,000 Australians aged 14+, Roy Morgan Research investigated in three different waves, of three years each, the share of Australians who consider themselves homosexual. Results are presented below by age and wave; total results per wave are displayed in the last column.[16]

Wave

Share of Australians considering themselves homosexual

14–19

20s

30s

40s

50+

TOTAL

2006–2008

2.9%

4.4%

2.5%

2.4%

1.3%

2.4%

2009–2011

4.0%

5.7%

3.8%

2.7%

1.6%

3.1%

2012–2014

4.6%

6.5%

4.2%

2.8%

1.7%

3.4%

In the last wave, 4.1% of men and 2.8% of women identified as homosexual. Men outnumbered women among homosexuals in all age groups. For both sexes, the share identifying as homosexual in the last wave was highest in the 20–29 age group (men: 7.6%, women: 5.5%).[16]

In an Ibope survey with a sample of 2,363 Brazilian Internet users weighted for national representativity, 83% declared themselves heterosexual, 7% homosexual, 5% bisexual, 1% other, and 4% refused to disclose their orientation. Twice as many male internet users as females identified as gay or bisexual (16% vs. 8%). People aged 18–29 were the most likely to identify as non-heterosexual (15%), followed by those aged 30–49 (10%). Only 5% of the population aged 50 or more consider themselves gay or bisexual. Among non-heterosexuals, 42% said they had no religion, compared to 13% of the heterosexual population. The Class B (middle class) had the highest percentage of non-heterosexuals (14%), followed by Class A (upper class, 11%). Classes C and D (lower–middle and low classes) had 10% gays and bisexuals. Among the Brazilian regions, Northern Brazil had the lowest percentage of non-heterosexuals (2%). All other regions had percentages at or above 10%, with the Center-West reporting the highest (14%).[17]

A study of 5,514 college and university students under the age of 25 found 1% who were homosexual and 1% who were bisexual.[18]

2012

In an interactive voice response telephone survey of around 2,700 Canadians, 5.3% identified as gay, lesbian, bisexual or transgender. Canadians aged 18–34 were much more likely to identify as LGBT (11.1%) than those in older brackets (2.6–3.4%).[19]

A study of 20,055 people found that 4.1% of the men and 2.6% of the women had at least one occurrence of sexual relations with person of the same sex during their lifetime.[28][29]

2011

In a nationally representative online survey of 7,841 French adults carried out by IFOP in early 2011, 6.6% of respondents identified as homosexual (3.6%) or bisexual (3%), and 90.8% as heterosexual. Compared to the heterosexual population, the homosexual population was much more likely to be male, single, and younger than 65, as well as to be living alone. Homosexuals were more likely to be economically active and work in "superior intellectual professions" but on average had a smaller household income. They were also more likely to be residing in big cities, especially in the region of Paris. The bisexual population had fewer statistically significant deviations from the heterosexual population, resembling the heterosexuals on some measures, homosexuals on others, or being at a midpoint on still some others. However, they were more likely to be aged 18–24 than the other two groups. Like homosexuals, they were also more likely to be single.[30]

In another IFOP survey of 9,515 French adults conducted later that same year, 6.5% of the sample identified as homosexual (3%) or bisexual (3.5%). Among LGBs, men outnumbered women by more than 2 to 1.[31]

2014

Based in a survey with about 10,000 respondents,[32] IFOP estimated that 90% of French people are heterosexual, 3% identify as bisexual, and 4% consider themselves homosexual. Two percent say they have not embraced a definition for their sexuality, and 1% did not wish to respond. More women than men are heterosexual (93% versus 86%), whereas more men than women identify as homosexual (7% v. 1%) and to a lesser extent bisexual (4% v. 2%). A homosexual or bisexual identity was more common in people aged 18–49 (9%) than among those aged 50–64 (6%) or over 65 (4%). More singles than people in relationships identified as homo- or bisexual (11% v. 6%). An LGB identity is also more common among people who said they have had more than 10 sex partners or none at all compared to those who have had intermediary levels of sexual experience. Catholics are more likely to identify as heterosexual (91%) than people who said they had some other religion or no religion whatsoever (88% each).[33]

2016

A female-only survey found that 4% of French women identify as gay or bisexual.[26] In the category of women aged less than 25, nine percent identify as bisexual and 1% as lesbian.[34]

2016 Paris survey

In a representative survey of Paris residents, IFOP that 79% of men and 90% of women identify as heterosexual, 13% of men and 1% of women are homosexual, and 6% of men and 4% of women consider themselves bisexual.[35]

According to Yougov,[36] the following is how German adults are distributed along the Kinsey scale (by age):

Sexual orientation of Germans (N = 1,122)

Age category

Exclusive heterosexuality

Predominant heterosexuality with incidental homosexual attraction

Predominant heterosexuality with common homosexual attraction

Bisexuality

Predominant homosexuality with common heterosexual attraction

Predominant homosexuality with incidental heterosexual attraction

Exclusive homosexuality

Do not know

All adults

63%

10%

5%

4%

1%

1%

3%

13%

Adults aged 18–24

45%

20%

11%

5%

1%

2%

2%

13%

2016

In a nationally representative, face-to-face survey with over 2,500 Germans (55% female), it was found that 86% of men and 82% of women identify as exclusively heterosexual, 3% of men and 4% of women are mostly heterosexual, 1% of each sex declared themselves bisexual, and 1.5% as predominantly or exclusively homosexual. Other sexual orientations were reported by 3% of men and 4% of women. One percent of each sex was uncertain. Four percent of men and 7% of women gave no answer.[37]

2017

A female-only survey found that 5% of German women identify as gay or bisexual.[26]

A study of the responses of 7,441 individuals, conducted by the ESRI, found that 2.7% of men and 1.2% of women self-identified as homosexual or bisexual. A question based on a variant of the Kinsey scale found that 5.3% of men and 5.8% of women reported some same-sex attraction. Of those surveyed, 7.1% of men and 4.7% of women reported a homosexual experience some time in their life so far. It also found that 4.4% of men and 1.4% of women reported a "genital same-sex experience" (oral or anal sex, or any other genital contact) in their life so far.[38] The study was commissioned and published by the Crisis Pregnancy Agency in partnership with the Department of Health and Children.

In a sample representative of the Israeli Jewish population aged 18 to 44, it was found that 11.3% of men and 15.2% of women self-reported attraction to the same-gender, 10.2 and 8.7% reported lifetime same-gender encounters, while 8.2 and 4.8% self-identified as gay or bisexual men and lesbian or bisexual women, respectively. A non-heterosexual identity was more common in Tel Aviv than in other parts of the country and, among men, it was also correlated with younger age.[39]

2015

In a survey employing the Kinsey scale, 4.5% of non-religious Israelis placed themselves on points 5 or 6 on the scale, indicating a homosexual orientation with minor or non-existent opposite-sex attraction, and 91.5% placed themselves on points 0 or 1, which indicates a heterosexual orientation with minor or non-existent same-sex attraction. In the category of young adults, aged 18 to 24, 7.4% placed themselves on Kinsey points 5 or 6, and 80% on points 0 or 1. Compared to the larger population, more young adults also placed themselves on point 3 of the Kinsey scale, meaning that equal attraction to both sexes (4.2% versus 1%), and on point 2, meaning a mostly heterosexual orientation with major homosexual attraction (7.4% v. 2.3%). Point 4 of the Kinsey scale, indicating a mostly homosexual orientation with major heterosexual attraction, contained a similar share of young adults and all adults (1.1% v. 0.7%).[40]

A random survey of 7,725 Italians (18–74 years old) conducted by the National Institute of Statistics between June and December 2011 with CAPI technique[41] found that about 2.4% of the population declared to be homosexual or bisexual, 77% heterosexual, 0.1% transsexual, 4% reported to be "other", 15.6% did not answer. An extended survey including all the people that during their lives fell or are in love with a same-sex individual, or that had sexual intercourse with a same-sex individual, increases the percentage to 6.7% of the population. More men than women, more northerners than southerners, more younger than older people identified themselves as homosexuals. Members of 7725 families spread over 660 Italian municipalities took part in the survey.[42]

2016

A female-only survey found that 1% of Italian women identify as gay or bisexual.[26]

In a face-to-face survey carried out by the Dutch National Survey of General Practice, of the 4,229 men with a valid answer to the sexual orientation question, 1.5% self-identified as gay, 0.6% as bisexual and 97.9% as heterosexual. Of the 5,282 women, 1.5% self-identified as gay, 1.2% as bisexual, and 97.3% as heterosexual.[46]

2009

In a nationally representative, online sample of 3145 men and 3283 women, 3.6% of the men and 1.4% of the women identified as gay. A further 5.5% of the men and 7.4% of the women identified as bisexual. Self-identification was assessed on a 5-point scale and all three non-exclusive options were combined for bisexual self-identification. Same-sex attraction is more prevalent than homo- or bisexual orientation. Of the men, 9.9% reported at least some same-sex attraction (4.2% exclusively). Among women, this was 10.9% (1.5% exclusively), of which a large group reported mainly heterosexual attraction. Of the men, 3.6% had had sex with men in the past six months and a further 2.0% with both men and women. For women, these percentages were 1.6% and 0.8% respectively. Gay or bisexual self-identification without same-sex attraction was almost non-existent. However, not all men and women who felt attracted to their own gender identified as gay or bisexual. Same-sex sexual behavior did occur among men and women who neither reported any same-sex attraction or a gay or bisexual identification, especially when lifelong sexual behavior was considered.[47]

2016

A female-only survey found that 8% of Dutch women identify as gay or bisexual.[26]

In an anonymous survey of 8,000 New Zealand secondary school students conducted by the University of Auckland, 0.9% of those surveyed reported exclusive attraction to the same sex, 3.3% to both sexes and 1.8% to neither.[48]

1993–2011

The Dunedin Multidisciplinary Health and Development Study is a prospective study that looked at changes in sexual behavior, attraction, and identity among around 1,000 New Zealanders born in 1972 or 1973. Samples were first interviewed in 1993, when they were 21, and again at ages 26, 32, and 38, in 2010/2011. The study found a strong decrease in the share of women who self-reported exclusive heterosexual attraction from age 21 (88.3%) to age 26 (82.5%), but a small increase at age 32 (84.2%) and again at 38 (87.6%). By contrast, among men, the share self-reporting exclusive heterosexual attraction remained largely stable between ages 21 (94.9%) and 32 (94.2%), with a small decrease at age 38 (92.9%). Sexual identity was only assessed at ages 32 and 38. At age 32, 0.9% of women and 1.3% of men self-identified as gay, and 2.9% of women and 1.7% of men as bisexual. Additionally, 1.5% of women and 2.2% of men identified as "other". At age 38, 1.1% of women and 1.7% of men self-identified as gay, and 2.6% of women and 3% of men as bisexual, with 1.1% of women and 0.2% of men identifying as "other". While sexual attraction changed more for women than for men, changes among men were more consistently to greater homosexuality, while changes among women past age 26 occurred equally in both directions (i.e., to both more and less heterosexual attraction). Researchers discussed several factors behind the changes, from age effects to cultural effects, with homosexuality, especially female homosexuality, becoming more socially acceptable in the West in the 1990s and 2000s.[49]

2013-2014

According to results from the fifth wave of the New Zealand Attitudes and Values Study, which interviewed over 14,000 people about their sexual orientation, 94.2% of New Zealanders identify as heterosexual, 2.6% as gay or lesbian, 1.8% as bisexual, 0.6% as bicurious, 0.5% as pansexual, and 0.3% as asexual.[50] No gender differences were found in the share of New Zealanders identifying as heterosexual (94.1% of men and 94.4% of women) or pansexual (0.5% of both men and women), but men were more likely to identify as gay (3.5%) than women (1.8%), and women were more likely than men to identify as bisexual (2.1% versus 1.5%), bicurious (0.7% v. 0.4%) and asexual (0.4% v. 0.1%). Women in all the non-heterosexual categories were significantly younger than women in the heterosexual category. Men in the gay, bisexual, and bicurious categories were also significantly younger than heterosexual men.[51]

A Young Adult Fertility and Sexuality Survey conducted in 2002 by the University of the Philippines Population Institute and Demographic Research and Development Foundation found that about eleven percent of sexually active young people aged 15–24 had sex with a person of the same sex. Of this figure, 87 percent were men having had sex with men.[54]

A volunteer-based research of adult Poles showed that different modes of survey produce significant differences in the share of people who admit homosexual attraction. In paper-based surveys, 6% of respondents self-reported same-sex attraction, compared to 12% of online respondents. There were no other significant differences in other aspects of sexual life, and the two sets of volunteers were similar in age, education, and geographical location.[55]

In a 2016 report titled: 'Progressive Prudes: A Survey of Attitudes towards Homosexuality and Gender Non-Conformity in South Africa' produced by the Other Foundation and the Human Sciences Research Council, the findings were that:
Approximately 430,000 men and 2,800,000 women present themselves in a gender non-conforming way,
530,000 men and women of all population groups, both rural and urban dwelling, and across age groups, self-identify as either homosexual, bisexual, or gender non-conforming in some way-the same ratio as observed in other countries around the world.

A female-only survey found that 6% of Spanish women identify as gay or bisexual.[26]

2017 'Barómetro Control' survey

The sixth edition of the Barómetro Control sexual behavior survey, which was performed in 2017, and is representative of the Spanish population aged 18 to 35, found that 89% of young Spanish adults identify as heterosexual, 6% as male homosexual, 3% as female homosexual, and 2% as bisexual.[56]

In an anonymous survey of 1,978 male high school students performed in 2003, respondents answered a question regarding same-sex attraction by choosing a number in a 5-point Likert scale (1 = no and 5 = strong). Those who marked the number 5 made up 4% of the sample and those who marked the numbers 3 or 4, presented by researchers as self-reporting "some" same-sex attraction, 7%.[53]

A study of 8,337 British men found that 6.1% have had a "homosexual experience" and 3.6% had "1+ homosexual partner ever."[57]

2005

HM Treasury and the Department of Trade and Industry completed a survey to help the government analyse the financial implications of the Civil Partnerships Act (such as pensions, inheritance and tax benefits). They concluded that there were 3.6 million gay people in Britain—around 6% of the total population or 1 in 16.66 people.[58]

2008

In a survey of around 1,000 Britons using a self-completed questionnaire, 2% of the total sample identified as bisexual, 4% as homosexual, and 92% as heterosexual.[59]

2009

In an online survey with over 75,000 Yougov panelists in Britain, 90.9% identified as heterosexual, 5.8% as gay, lesbian or bisexual, 1.3% opted not to give an answer, and 2.1% gave other reasons.[60] The sample was recruited to closely match the overall British population on demographic variables such as age, gender, employment status and socio-economic classification.[60] Among men, around 89% identified as heterosexual, 5.5% identified as gay, and 2.5% as bisexual. Straight women constituted around 93% of all women, lesbians were 1.4%, and bisexual women 2.3%. A little over two percent of each sex identified as "Other", and a little over 1% did not want to indicate a sexual orientation. Non-heterosexuals tended to be younger, and this was especially the case for bisexual women and gay men, whose average ages were 32 and 36 respectively, compared to an average of 47 among heterosexuals. Ethnic minorities were less likely to identify as gay or lesbian than Whites (1.4% vs. 3.5%) but were more likely to prefer not to disclose their sexual orientation (7.5% vs 0.9%). Sexual minorities tended to concentrate more in certain parts of the country — in London especially, where 27% of gay men and lesbians, as well as 19% of bisexuals, took residence, compared to only 14% of heterosexuals. Employment status also correlated with sexual orientation, as more gay than straight men worked full-time (three quarters v. 57%), and the same was true among women (lesbians: 58%, straight women: 41%). Similarly, gay men (73%) and lesbians (66%) were overrepresented among the upper classes (classes ABC1), though the difference between heterosexuals and bisexuals (54% v. 58%) was not statistically significant. LGB people — especially lesbians — also had on average higher educational achievement.[60]

The study argued for the need to provide strong anonymity to respondents in order to gauge the true size of the non-heterosexual population, as more LGB than heterosexual respondents indicated they would be less likely to disclose their true sexual orientation in a face-to-face interview than in a self-administered, online survey.[61]

2014

In an anonymous online sex survey carried out by The Observer on the sex lives of the British, 4% of the 1,052 samples surveyed identified as gay or lesbian, and another 4% as bisexual.[62]

2014

In a nationally representative Survation study of 1,003 British women, 92% identified as heterosexual, 1.6% as gay or lesbian, 3.5% as bisexual, 0.3% as other, and 2.6% refused to disclose their sexual orientation. Sexual orientation appeared to be linked with age. Millennial women, aged 18–34, were significantly more likely to identify as bisexual (6.6%) than women aged 35–54 (1.4%) or older women (0.7%). Age differences were smaller for lesbian identity, but the pattern was the same, with 1.9% younger women identifying as lesbian, compared with 1.6% of middle aged and 1.3% of older women. Heterosexual identity followed the opposite pattern, being highest among older women (95.3%) and lowest among Millennials (89.1%). Sexual identity was also strongly correlated with childlessness, with 9.6% of childless women identifying as gay or bisexual, compared with 3.6% of women with underage children, and 0.5% of women with adult children.[63]

2015

In a Yougov survey of 1,632 adults, 5.5% identified as gay, 2.1% as bisexual, and 88.7% as heterosexual.[64] Asked to place themselves on the Kinsey scale, 72% of all adults, and 46% of adults aged 18–24 years, picked a score of zero, meaning that they identify as totally heterosexual. Four percent of the total sample, and 6% of young adults, picked a score of six, meaning a totally homosexual identity.[65]

In all years, it was observed that an LGB identity is most common among London residents and those aged under 35. Homosexual identity in 2016 was more than twice as common among men (1.7%) than among women (0.7), whereas bisexual identity was more common among women (0.9%) than men (0.6%).

2016

A female-only survey found that 4% of British women identify as gay or bisexual.[26]

2016

The United Kingdom Office for National Statistics [68] Annual Population Survey reported over 1 million (2.0%) of the UK population aged 16 and over identified as Lesbian, Gay or Bisexual (LGB). This represented a statistically significant increase from 1.7% in 2015. [69]

2017

In a Survation poll on adults aged 40–70, 92.5% identified as heterosexual, 3.5% as gay, 2.4% as bisexual, 0.5% as Other and 1% did not want to reveal their sexual orientation. Those under 60 were less likely to identify as heterosexual than those aged 60–70. A gay identity was more common among men (6.1%) than women (1%), and the opposite was true of heterosexuality (men: 89.9%, women: 95%). No differences were found in the share identifying as bisexual (2.4% versus 2.5%). London had a higher share of middle aged or older people identifying as gay (8%) or bisexual (6%) than other parts of the country.[70]

2017

According to a nationally representative study organized by Kantar TNS, 87% of British men aged 18 to 30 years identify as heterosexual, 7% as homosexual, 5% as bisexual, and 2% as other.[45]

2017 BBC generational survey

An Ipsos MORI survey on behalf of BBC[71] found that British people aged 16–22 (also called Generation Z) have lower odds to identify as exclusively straight (66%) than those who belong to the Millennial generation (71%), Generation X (85%), or Baby Boomers (88%). Within Generation Z, there were several important gender differences in sexual identity: young men were more likely to identify as completely heterosexual than young women (73% v. 59%) whereas young women had higher chances to identify as non-exclusively straight (19%) and bisexual (14%) than young men (10% and 5%, respectively). There were no significant gender differences in the share identifying as predominantly or exclusively homosexual (5% for each sex), but Generation Z men were significantly more likely to refuse to disclose their sexual orientation (7%) than their female counterparts (3%). Significantly more white youth identified as exclusively homosexual (3%) than those of ethnic minority backgrounds (0%) but no other ethnic differences were found. Exclusively heterosexual youths were also less likely to describe themselves as fairly or very active in politics, but they were more likely to believe that they enjoy a better life than Millennials.

Among older adults, there were no differences in the share of men (82%) and women (80%) identifying as exclusively heterosexual. But more women than men identified as mostly heterosexual (11% v. 6%), while more men than women identified as exclusively homosexual (4% v. 2%) and mostly homosexual (2% v. 0.4%). Exclusive heterosexuals were more likely to have voted "Leave" on the 2016 UK referendum to leave the European Union, whereas mostly heterosexuals and exclusive homosexuals were overrepresented among "Remain" voters.[72]

According to many a source, from academic researchers[73][74] to pollsters[61][75] to market research groups,[30][76] the population that identifies as LGBT and/or has had sexual relations with the same sex may be underestimated in surveys that employ live interviewers to collect data. Their argument is that methods stronger in anonymity and/or confidentiality, such as online questionnaires and IVR interviews, are better than more traditional survey modes at gauging the size of the non-heterosexual population.

British researchers with the third wave of the National Survey of Sexual Attitudes and Lifestyles (NATSAL) addressed this matter in one of their studies. Interviewers collected data on sexual behavior from a sample of over 15,000 subjects at their home. However, a portion of respondents agreed to complete an online questionnaire asking many of the same questions asked live before. The questionnaire was to be taken one to two months after the original interview. The data below were extracted from the same group of 202 men and 325 women who gave out information about same-sex experiences live and then successfully completed the online questionnaire later. Numbers show how answers varied between survey modes and the information is given on whether the difference between methods was significant or not.[77]

Partial data from the NATSAL-3

Any same-sex experience

Any same-sex sex (experience with genital contact)

Face-to-face

Online

Statistically significant difference between methods?

Face-to-face

Online

Statistically significant difference between methods?

Men

11.4%

17.3%

Yes

9.9%

13.5%

Yes

Women

14.5%

19.7%

Yes

9.2%

10.5%

No

Researchers from other countries have produced similar findings. In Poland, for example, it was found in an experiment that self-reporting same-sex attraction was twice as common using an online questionnaire as in a paper questionnaire, despite the fact that the group that answered the online questions and the one that filled out the paper form were similar on all demographic variables and on all other aspects of their sexuality.[55] In the 90s, an experiment was made in the US where it was found that teen males were several times more likely to acknowledge same-sex experiences using a computer methodology compared to paper questionnaires.[78]

In general, most research agrees that the number of people who have had multiple same-gender sexual experiences is fewer than the number of people who have had a single such experience, and that the number of people who identify themselves as exclusively homosexual is fewer than the number of people who have had multiple homosexual experiences.[original research?]

In addition, shifts can occur in reports of the prevalence of homosexuality. For example, the Hamburg Institute for Sexual Research conducted a survey over the sexual behavior of young people in 1970 and repeated it in 1990. Whereas in 1970 18% of the boys ages 16 and 17 reported to have had at least one same-sex sexual experience, the number had dropped to 2% by 1990.[79][80]

Data from the General Social Survey shows that the percentage of Americans reporting predominately same-sex partners remained stable between 1989 and 2014. In contrast, the percentage who reported ever having a same-sex partner increased.[81] By contrast, the National Survey of Family Growth has found an increase in the share of men and women who self-report a bisexual orientation in their 2011–2013 study compared to previous surveys.[82] Likewise, in the Second Australian Study of Health and Relationships, whose data was collected in 2012 and 2013, researchers noticed significant growth in the share of women who report bisexual orientation and attraction, and the share of men who report exclusive homosexual attraction, compared to the results of the First Australian Study of Health and Relationships, executed in 2001.[14]

The Williams Institute at UCLA School of Law, a sexual orientation law think tank, released a study in April 2011[84] estimating based on its research that 1.7 percent of American adults identify as gay or lesbian, while another 1.8 percent identify as bisexual. Drawing on information from four recent national and two state-level population-based surveys, the analyses suggest that there are more than 8 million adults in the US who are lesbian, gay, or bisexual, comprising 3.5% of the adult population. Of men, 2.2% identify as gay and an additional 1.4% as bisexual. Of women, 1.1% identify as lesbian and an additional 2.2% as bisexual.

These charts show lists of the cities and the metropolitan areas with the highest LGB population in terms of numbers of total gay, lesbian and bisexual residents, based on estimates published in 2006 by the Williams Institute of the UCLA School of Law.[85]

^ abLe profil de la population gay et lesbienne en 2011(PDF) (Report) (in French). Retrieved 1 May 2015. Due to the intimate and sensitive subject addressed (sexuality), IFOP has chosen to use a self-administered online method. In fact, this survey mode offers respondents the possibility to speak about themselves without taking the risk of being judged by the interviewer.